儿童肾病综合征致病基因筛查策略的探讨

目的 通过儿童散发性肾病综合征（NS）致病基因及其突变特点，探讨儿童NS致病基因的筛查策略。方法 收集复旦大学附属儿科医院肾脏风湿科2011年1月1日至2013年12月31日的所有住院NS患儿的临床资料,依据发病年龄分为先天性NS（3月龄内）、婴儿型NS（～12月龄）、儿童早发型NS（～5岁）和儿童迟发型NS（～14岁）；对儿童早发型和迟发型NS再依据对糖皮质激素（GC）治疗反应分为GC敏感（SSNS）和GC耐药（SRNS），SRNS又分为初发型和迟发型SRNS。先天性NS行NPHS1、NPHS2、PLCE1、LAMB2、LMX1B、COQ2基因所有外显子和WT1基因8、9外显子直接测序；婴儿型NS行NPHS1、NPHS2、PLCE1基因所有外显子和WT1基因8、9外显子直接测序；儿童早发型和迟发型NS行NPHS2基因所有外显子和WT1基因8、9外显子直接测序，以及NPHS1等8个基因42个常见突变位点的SnapShot分析。结果 238例NS患儿进入本文分析，男139例。①8/10例（80％）先天性NS患儿检出NPHS1基因致病性突变；②12例婴儿型NS患儿检出3例WT1（25.0%）、2例NPHS2（16.7%）和1例NPHS1（8.3%）基因突变；③8/132例（6.1％）早发型NS患儿检出基因突变，均属于初发型SRNS（8/32，25.0%），其中WT1 3例（9.4％）、NPHS2 2例（6.3%）、NPHS1 2例（6.3%)和INF2 1例（3.1%)，19例迟发型SRNS和81例SSNS患儿均未检出相关基因突变；④84例儿童迟发型NS中未检出基因致病性突变。结论 先天性NS、婴儿型NS和儿童早发型NS中的初发型SRNS患儿应是临床基因筛查的对象。NPHS1是本文先天性NS患儿的主要致病基因，推荐在先天性NS患儿行NPHS1基因检测。NPHS1、NPHS2和WT1基因突变频率在婴儿型NS和儿童早发型NS中的初发型SRNS患儿中较高，推荐这些人群中优先选择这3个基因作为目标基因进行筛查。不推荐常规在SSNS和迟发型SRNS患儿中行基因检测。

Studies on Strategy of gene screening in Children with nephrotic syndrome

Objective To explore causative genes of nephrotic syndrome(NS) in children and its mutant characteristics. Methods All NS children in Children's Hospital of Fudan University from Jan. 1st, 2011 to Dec. 31th, 2013 were enrolled. The clinical data including medical records and follow-up information, and peripheral blood were collected. Firstly, NS was classified into familial and sporadic NS according to family history. Then sporadic NS was divided into congenital NS (CNS), infantile NS, early-child NS and late-child NS in accordance with the age of onset. Early- and late-child NS were divided into steroid-sensitive NS (SSNS) and steroid-resistant NS (SRNS) on the basis of initial sensitivity to glucocorticoid, and then SRNS was divided into initial- and late-resistant SRNS. NPHS1, NPHS2, PLCE1, LAMB2, LMX1B, COQ2 and WT1 genes were tested in patients with CNS by direct sequencing, while NPHS1, NPHS2, PLCE1 and WT1 were tested in patients with infantile NS. To early- and late-child NS, NPHS2 and WT1 were tested by direct sequencing, 42 common gene mutations in 8 main genes, like NPHS1 was tested by SnapShot analysis. Results Causative mutations in NPHS1 was found in 8 cases (80%), none mutations in NPHS2, PLCE1, LAMB2, LMX1B, COQ2, or WT1 gene was found in 10 CNS cases. 6 out of 12 cases with infantile NS had mutations, 3 of which was in WT1 gene, 2 in NPHS2 gene, and 1 in NPHS1 gene. In 132 cases of early-onset NS children, 8 cases (6.1%) with initial SRNS had gene mutations. WT1 gene mutation was found in 3 cases (3/32, 9.4). NPHS2 mutations were detected in 2 patients (2/32, 6.3%). NPHS1 mutations were identified in 2 patients (2/32, 6.3%). INF2 mutation was found in one case. No mutations were found in early-child NS children with late SRNS or SSNS. There were no causative mutations of tested genes detected among 84 cases of late-child NS children. Conclusion Candidate gene screening should be performed in congenital and infantile NS as well as in early-child NS children with initial SRNS. High frequency of mutations in NPHS1, NPHS2 and WT1 was found in children with infantile NS and early-child NS children with initial SRNS. NPHS1 is a common causative gene in this study. Mutational analysis is suggested in children with congenital NS. Routine gene screening is not suggested in children with late SRNS and SSNS.